I know rotary engines are sweet and can be slam bang powerful, the replacement of apex seals was what I was equating to the issues with the seals on a Coates head system.

The idea I am addressing Tom, is simple smooth rotation in the engine, like a Wankel, but in the heads of an engine.

I wish I was smarter, better employed, and better set financially, I'd have you guys fireball my bullet in an instant, It would add to my Klingon Battle Prowess! (hee hee)

And I would never want you guys to let all your secrets out of the bag, it would be like knowing how the magic trick works...

But are we all in agreement that the idea of a system of internal or for that matter external combustion, that uses a rotational system without a TDC and BDC, but somehow manages to harness the explosion in a manner so as to smoothly and with longer life and higher rev potential and therefore (hopefully) power potential, is a worthy goal.

And I am the original "hijacker" here...

my posts simply fell in here due to the discussion of heads and flow and whatnot, it sort of mushroomed from there.

On another note, the only engine styles that I know of that do make better use of the existing technology are boxer engines, and radial airplane engines, as far as power usefulness and balance of load and all that jazz...

I love radial engines.... (falling into a state of dreaming, tongue lolling out and visualizing P&W R985s in a Grumman Goose... "drool")

Logged

"Counted his friends in burned-out spark plugsand prays that he always will.

But he's the last of the blue blood greaser boys all of his mates are doing time:

Married with three kids up by the ring roadsold their souls straight down the line.

I't would be great to come watch the first event this engine is used for!

Please keep us up to date

Hi Nixie!

We are all excited about the prospects for this year's effort with the new engine. I'm sure that it will take some sorting. After all, it is now able to flow WAYYY more air than any Bullet ever could before(except maybe Linsdell, and we don't know what he has). At any rate, this is going to give him a run for his money, that's for sure.

I don't know how much Paul is wanting to say about the head in public, so I will wait until he decides about what is to be said, or what isn't.

From my point of view, we have never done any Bullet head that has the performance potential of this head. This is the best we have ever done.

Ace, you can say whatever you like about the head work, including before / after flow figures for it. I know I ported the head by hand previously, using pretty crude and basic methods, but it worked well like that and soon it will work better. I think the flow figures for my previous efforts will be respectable enough to share here, along with the new, improved ones as a comparison. I was told a few years ago at Cadwell Park, as we watched our 350 Clipper beat that year's champion, Graham Buller back to 3rd place on his very quick Manx Norton 350 - [the Clipper came second to Tim Jackson [AJS 7R if I remember right] in the last race of the last meeting] - that I tune my bikes using 'brute force' rather than finesse - well now we will be mixing brute force with finesse, could be a knock out combination! B.W.

First, as Paul said, the head came in with a very decent flowing port to begin with. He had done a very good job with it, especially for someone who wasn't working with a flow bench. So, hats off to Paul for a job well done there!

The flow bench tests were very revealing. We flow tested the ports all the way up to .600" lift, because that was the lift goal that we had in mind for the new head mods. I'll discuss primarily the inlet port here, because the exhaust port will just flow a percentage of the inlet, and we adjust it to suit.

Paul's inlet port as it came to us flowed 263 cfm at .600" lift. This is a hefty amount of flow, and it should support 60hp in a race engine like that.So, how come it wasn't making 60hp?Well, this is where the interesting part comes in.

In the Bullet, the cams are located on spindles which are close to the crankshaft seal area in the timing chest. This means that the cams cannot withstand much lobe enlargement, or they hit the case around the crankshaft oil seal. So, even with all the creative methods for dealing with cam lobes to get bigger ones in there, the biggest lobes that I have ever heard about are .442" peak lift, and that takes a bit of clever work to get them in there. This means that cam lobe lift is limited in the Bullet to about that figure, or less.

In the case of the Bullet Whisperer engine, it was using a different cam with about .420" peak lift, which is still quite a hefty lobe size for a Bullet. This is also the case with virtually all of the Bullets out there in the racing world, because there are only a few cams to pick from, and there's a limit to how high they can lift at the lobe, so everybody out there on the track is running similar lift in their Bullets. So, this isn't Paul's fault. It's what everybody out there has to face with their Bullet engines on the track. It's afflicting all the racers, and the street hot-rodders too. Cam lift is too limited.

So, what does this mean?This means that even though the head could flow a very good amount of air at .600" lift, this engine never could lift to .600", and could only lift to .420", so the amount of air it could let through was limited by that valve opening to about 220 cfm, according to our flow tests. So essentially, the head had a port that was too big for the valve lift available from the cam. What was needed was to exploit that existing flow available at the higher lifts, and that's what we did.

First, we knew where we were going with the lift, because we had already developed that kit, and although Paul was getting higher lift than we had ever done with that kit before, we figured we could squeeze .600" out of it, so we looked at the ports and assessed the improvements we could make on it, to make it even better than it was.The first thing we saw was that the port angle was a little lower than we would have preferred. It made a fairly sharp short turn on the floor, and we feel that was cutting down the flow because it couldn't use the entire circumference of the valve to flow the mixture in. It was way too costly to weld up the entire port, and start over with a completely new port angle. So, we worked with the lower port angle, and it came out nicely. Flows PLENTY.It's now peaking flow at 285 cfm at .600" lift. And since we can access .600" lift with our roller rocker kit now, we can use every bit of that flow to make power.

Since the port size was already set at the usual 1.5" size that is seen in the Fury heads, and is able to reach somewhat over 8000 rpm, we did not change that size, but just re-shaped it to achieve the flow increases. And to make the most from this flow, a higher rpm limit is necessary to make the additional horsepower we want. So, the rpm limit is going up now.

To this end, a lot of lightening of parts was involved, including titanium valves and beryllium-copper valve seats, lightweight racing springs and titanium retainers, alloy roller rockers, custom valve guides, etc. The full kit of high rpm goodies went into this head.

The alloy roller rocker kit with high ratio is basically the same kit which we previously designed for the Big Head, but in this instance the desire was to use a bigger cam than the Ace cams which were part of the original kit. So, this meant that we needed to be able to make provision for .600" lift, instead of the .510" lift that we had in the last head we did with this kit. This presented some issues, but in the end we got it in there. It's the most lift we have ever gotten in a Bullet head.

And to tie it all together, we now have a racing Bullet which is finally going to reach a higher level of potential than ever before. This bike is a methanol-burning, ultra-high compression, very high rpm, racing engine which should be able to use all the flow we are providing here.And while I am not going to make predictions about what the horsepower is going to be, I will say that it's going to make a LOT more hp than it did before. If the guidelines of flow to hp are correct in this application, it has the possible potential to hit 60 hp at the rear wheel. Since things rarely are perfect, we could expect it to end up somewhere in the 50's for hp at the rear wheel.

Basically, the estimation figuring would go like this.The "rule of thumb" for estimating hp from head flow is that hp at the crank should be 25.6% of the peak cfm flow of the head, in a full-race prepared engine.If we take our 285 cfm, and subtract about 20 cfm for the flow losses involved from adding the manifold and carb on, that leaves us with about 265 cfm for the complete inlet tract.25.6% of 265 cfm is 67.84 hp at the crankshaft, theoretically, if everything goes perfectly, and the moon aligns with the stars.Subtracting the typical 7hp in drivetrain losses that we normally see with the Bullet, and that would leave 60 hp at the rear wheel, theoretically.Since things are rarely theoretically perfect, we can expect some lesser amount, hopefully not too much lower. I am hoping for 56-58 hp at the rear wheel.

Whatever it ends up with, it's going to be way more powerful than any other Bullet out there that isn't running our kit, and it's going to be way more powerful than it was before. I am very keen to see how much can actually be gotten out of this thing in the real world, and not just theoretical. It has tons of promise. If any Bullet head has the chance to do these kinds of horsepower numbers, it's this head. It has the most of everything that we have ever done, or have ever seen in any Bullet head.

Had a long Skype conference with B.W. and the race team today. Went very well. Just tying up the last few things now.Very much looking forward to seeing what this kit will do on the track in the real world.

Man that is Vincent BS HP specs which had a top speed of 125 mph and is also about 150 - 175 pounds heavier than a Bullet. This bike when completed should be listed in the single cylinder monster category.

Man that is Vincent BS HP specs which had a top speed of 125 mph and is also about 150 - 175 pounds heavier than a Bullet. This bike when completed should be listed in the single cylinder monster category.

I can only estimate the hp based on the fact that it has enough flow and compression and rpm to meet those estimates. We don't really know what the real world hp will actually be until it is done and sorted, and on the dyno.It may or may not meet the estimates. I'm optimistic that it will.

Ace , I think you just gave away all your industrial secrets. I can hear compittion / opposition grinding away in there work shops now.The Bullet Whisperer may have to consider installing an antique super charger just to stay ahead of the pack on race day.